Electron discharge device



3 Sheets-Sheet 1f M KNOLL ELECTRON DISCHARGE DEVICE Filed June 25, 1934 I INVENTOR MAX KN 0 LL ATTORNEY V May 28, 1935. KNOLL 2,002,667

ELECTRON DISCHARGE DEVICE 3 Sheets-Sheet 2 Filed June 23, 1934' \NVENTOR MAX KNOLL ATTORNEY M. KNOLL ELECTRON DISCHARGE DEVICE Filed June 23, 1934 III. 'I/II/Il'I/IA 'IIIIIIIII 5 Sheets-Sheet 3 INVENTOR MAX KNOLL ATTORNEY Patented May 28, 1935 UNITED STATES 2,002,667 ELECTRON DISCHARGE DEVICE Max Knoll,

Berlin, Germanyfassirnor to Telefunken Gesellschaft fiir Drahtloee Telegraphic m. .b. 11., Berlin, Germany,

Germany a corporation of Application June 23, 1934, Serial No. 732,045 In Germany June 29, 1933 12 Claims.

My invention tubes and more particularly to the mounting and structure of an electrode system in which use is made of a ceramic body to support and space 6 the various electrodes.

The present invention has for its object to simplify the assembling of the electrode systems and to render the electrode system especially stable and rugged by using as a support for the electrode system a unitary or multi-part ceramic body, which is provided with a cavity or hollow space for accommodating the heater body, an indirectly heated cathode being used, and which is provided with surfaces formed to receive the other electrodes. This method of assembly and its use in actual practice is favored by the fact that by modern technological methods these ceramic bodies can be produced with extreme accuracy. By this method all finishing or trimming or adjustment work is eliminated since the tolerance limits can be made very narrow, and this means in largescale manufacture that the cost of production is reduced, the amount of scrap or waste is reduced, and that a high-grade product can be obtained. Inasmuch as it is feasible to make the cathode support in one piece or integral with the supports for the other electrodes, not only is construction simplified but in addition there is the further advantage that the mechanical and thermal properties of the cathode support and the means for retaining these properties are no longer a problem. Furthermore, because of the electrode mounting thus made possible, there results a considerable reduction of the amount of energy required for heating a cathode having a given electron emitting surface.

, The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawings in which Figure 1 is a longitudinal cross section of an electron discharge device embodying my invention; Figure 2 is a horizontal cross section taken along the line 2-2 of Figure 1; Figure 3 is a longitudinal cross section of a modification of the electron discharge device shown in Figure l and embodying my invention; Figure 4 is a horizontal cross section taken along the line 4-4 of Figure 3; Figure 5 is a longitudinal cross section of a still further modification of an electron discharge device embodying my invention relates to electron discharge and Figure 6 is a horizontal cross section taken along the line 6-6 of Figure 5.

The four-electrode tube or tetrode shown in Figures 1 and 2 is provided with the glass bulb or envelope I having an external press 2. The cathode comprises a central ceramic tube 3 closed at one end and terminating in a flange 4 with another flange 5 of similar construction fitted upon the other and open end of the tube 3. The heater winding 6 is mounted inside the ceramic tube 3. The outside surface of the tube 3 has a metallic coat or sleeve 1 consisting, for example. of a metallic tube slipped over the ceramic tube, or produced by spraying a metallic layer or film on the ceramic tube and applying electron-emissive material to the surface of the metallic layer. The two grid electrodes 8 and 9 are provided at their ends with annular stiffening or reinforcing collars Ill and H, which are supported in annular grooves l2 and 13 in the flanges 4 and 5. The tubular plate or anode [4 consists of a cylinder of solid sheet metal to which attaching eyelets l5 are welded. In order that the flow or transmission of heat from the body of the cathode to the anode or plate may be rendered as difllcult as possible, the cylindrical plate is not supported around its entire inner circumference, but only at spaced points upon the ceramic flanges. This is accomplished by radially and outwardly extending lug-like projections I6 on the flanges 4 and 5. The tubular plate is closed at both ends by cover plates or shields l1 and I8. The cover plate or end shield i1 is secured to the tubular plate 14 by welding for example, and the top plate or shield is secured to the plate by the springs l9. Secured upon the cover plate I8 is the grid support 20. The two cover plates I1 and K8 are supported in spaced relation with the flanges 4 and 5 by the longitudinally extending lugs 2| spaced around the outer face flanges 4 and 5. The assembly of such an electrode system is extremely simple because the various parts are fitted together in sequence and are combined into a unit by closing the cover IS. The whole system is then mounted on the supports 22, which are slipped into eyelets l5 and secured thereto by welding. Finally, the electrode leads 23 extending thru the cover H are electrically united with the lead-in wires 24 in the press.

The above described construction of an electrode system offers the following thermal advantages. By the use of an outermost electrode enclosing the other electrodes of the mount, useless radiation of heat dissipated by the cathode, especially in the axial direction of the cathode, is prevented. As a consequence it is possible to use cathodes with smaller heating requirements 5 than in the usual type of electrode system where the cathode is open at both-ends. In addition this closed type of anode confines the electrons to the discharge'path between the electrodes, thus preventing undesirable space charges between the anode and the envelope of the tube and eliminating secondary emission from the glass envelope.

The embodiment of the invention in a three pof two mesh-type grids each supported on a metallic ring and secured to the ceramic body by connecting stays 36 welded to the rings. Owing to the fact that the supporting surfaces on which the grid and anode electrodes rest is limited to only a few spaced points, the transfer of heat between the electrodes thru the supports is reduced over the usual, arrangement. The

central opening of the disc 30 is-covered upby means of two plates which are provided with an electron-emissive coating. The anode comprises the two plates 34 and a .ring or-collar 31 secured on one edge to one of 'the'plates 34.

The other plate is supported in place against the lugs 32 by the, aid of a plurality of springs "a 33 spaced around the circumference of the ring W31, the electrode system being thus held tog'ether. The electrode system thus forms a closed mechanicalunit, and is supported on supporting wires or stays l0 sealed in the press and threaded thru and welded to the eyelets 39 attached to the ring 31.

As has been pointed out above, by means of the electrode system made in accordance with my invention smaller heating power than has heretofore been customary is possible. Inasmuch as the quantity of heat radiated towards the outside of the electrode system is less, there is an opportunity to reduce the surface area of the glass bulb. This would be valuable especially in the case of tubes intended to be employed in small sized equipment in which 0 space utilization is highly desired.

The modificationof an electron discharge device embodying my invention, shown in Figures 5 and 6, is a triode having an electrode system similar to :that shown in Figures 3 and 4. The ceramic body 50 of disc shape, supports the heater winding 5| threaded thru apertures 52 in the central depressed portion of the body 50. These depressed' portions are filled with refractory insulation 53, for example, magnesia, and

a two plates 54 are then riveted together over these filled in depressed portions, These plates may be provided on theoutside with a metallic layer having an electron-emissive coating. The body 50 is provided with lugs or projections 56 which serve as a support for the anode. The grid electrode comprises two rings 51 upon which is stretched a metalnetwork or gauze, the rings 51 being pressed against the ceramic body by the springs 53 or equivalent means. The anode forming a closed body consists of a metal cylinder 59, a plate 60 secured thereto,-preferably by welding, and a second plate 6| pressed against the ceramic body 50 by the spring 62, so that the entire electrode system is held together as a unit. The diflerent electrodes are provided with leads 63. r The glass vessel is lenticular in shape, and it is composed of two symmetric halves 64 and which are provided with an annular flange which forms the press. The two halves 64 and 65 of the envelope are so formed that the electrode system is pressed by action of the spring 62 against the inside wall of the envelope so that separate supporting stays or wires are unnecessary. For this reason the electrode leads 63 couldbe'made of stranded wires (litz wire). a

While I have indicated the preferred embodiment of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be'apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in-the appended claims.

What I claim as new is,

1'. An electrode system for an electron dis-. charge device, including-a ceramic tube provided with flanges at opposite ends thereof, a heater supported'within the tube and a plin'ality of electrodes supported between said flanges and concentric with said tube.

' 2.An electrode system for an electron discharge device, including a tube of ceramic ma terial provided with flanges at opposite 'ends thereof, a heater supported within said tube, a cathode surrounding saidtube, and'a plurality of electrodes supported between said flanges and concentric with said cathod 3. An electrode system for an electron discharge device, including a tube of ceramic ma terial provided with flanges at opposite ends thereof, lugs spaced around the periphery of said flanges, a heater supported within said tube, a cathode surrounding said tube, a plurality of electrodes concentric with said cathode and supported between said flanges and an outer electrode concentric with said cathode and said other electrodes and supported on the lugs on the periphery of said flanges.

4. An electrode system for an electron discharge device including a tube of ceramic material having outwardly extending flanges at opposite ends thereof, a, heater within said tube, a cathode supported on the outside surface of said tube, electrodes concentric with said cathode supported between said flanges, a concentric outer electrode supported on said flanges, and

cover plates for closing the ends of the outer electrode and supported on said flanges.

5. An electrode system for an electron discharge device including a tube of ceramic material having outwardly extending flanges at opposite ends thereof, lugs spaced around the periphery of said flanges, a heater within said tube, a cathode supported on the outside surface of said tube, electrodes concentric with said cathode supported between said flanges, a concentric outer electrode supported on said lugs, a cover plate secured to said outer electrode for closing one end of said outer electrode and a second cover plate for closing the other end of said outer electrode, and springs fastened to said outer electrode for maintaining said second cover plate in position.

6. An electrode system for an electron discharge device including a tube of ceramic material having outwardly extending flanges at opposite ends thereof, lugs spaced around the periphery of said flanges, a heater within said tube," a cathode supported on the outside surface of said tube, electrodes supported between said flanges concentric with said cathode, an outer electrode supported on said lugs concentric with said outer electrodes, a cover plate secured to said outer electrode for closing one end of said outer electrode and a second cover plate for closing the other end of said outer electrode and springs fastened to said outer electrode for maintaining said second cover plate in position against the lugs, and eyelets on said outer electrode adapted to receive the supporting wires.

7. An electron discharge tube having an envelope, a unitary electrode system within said envelope including a ceramic base for supporting a heater, a cathode and a plurality of electrodes in spaced relationship and provided with lugs, an outer electrode supported on said lugs around said heater, cathode and other electrodes, said unitary electrode system being maintained in position within the envelope of the tube by means of a spring pressing the electrode system against the inner wall of the envelope.

8. An electrode system for an electron discharge device including a ceramic tube having flanges at opposite ends thereof, said flanges being provided with concentric annular grooves on the inner faces thereof, outwardly extending radial lugs and longitudinally extending lugs on the outer periphery of said flanges, a heater within said tube, a cathode sleeve supported on the outside of said tube, concentric grid electrodes between said flanges and having their ends supported in the annular grooves in said flanges, a concentric anode supported on said radially extending lugs, end shields supported on said longitudinally extending lugs for closing the ends of said anode, eyelets on said anode and supporting wires extending thru said eyelets and welded thereto.

9. An electrode system for an electron discharge device comprising a disc shaped supporting member of insulating material, a heater wire supported centrally of said disc shaped member, flat cathode members mounted on opposite sides of said disc supporting member to be heated by said heater wire, flat mesh-like grids supported on said disc shaped supporting member on the outside of and in spaced relation with said cathode members, oppositely extending longitudinal lugs spaced around the periphery of said disc shaped supporting member and flat anode electrodes supported on said lugs in spaced relation with said cathodes and said grids and a collar adjacent to and fastened to the outside edges of said anode members.

10. An electrode system for an electron discharge device comprising a disc shaped ceramic support, a heater wire positioned centrally of said disc, cathode disc members supported on opposite side of said ceramic disc to be heated by said heater, grid electrodes comprising mesh discs spaced from said cathode discs by means of rings concentric with said cathode discs and supported on said ceramic support, longitudinally extending lugs spaced around the periphery of said ceramic support and disc like anode members mounted on and spaced from said grid members by said lugs, and a ring shaped member secured to the periphery of said anode discs for forming an enclosed electrode system.

11. An electrode system comprising an outer electrode in the form of a hollow container closed at one end, an inner electrode assembly received within said outer electrode and comprising a ceramic tube having flanges at opposite ends thereof and provided with lugs for spacing said flanges away from said outer electrode, a plurality of electrodes supported between said flanges around said tube, a heater received within said tube and a cover member for the open end of said electrode and springs for maintaining said cover member in engagement with the end of said outer electrode.

12. An electron discharge tube having an envelope, a unitary electrode system within said envelope and including a ceramic base for supporting a heater, a cathode and at least one other electrode in spaced relationship, lugs on said ceramic base, an outer electrode surrounding said heater, cathode and other electrode and supported on said lugs and means for supporting said electrode system within the envelope.

MAX KNOLL. 

